1. Field
The disclosed concept pertains generally to vacuum interrupters. The disclosed concept also pertains to retaining clips for vacuum interrupters. The disclosed concept further pertains to methods of assembling vacuum interrupters.
2. Background Information
Vacuum interrupters are often employed as the switching devices in power circuit breakers. Vacuum interrupters generally include separable electrical contacts disposed within an insulated and hermetically sealed vacuum chamber. The vacuum chamber typically includes, for example and without limitation, a number of ceramic sections (e.g., without limitation, a number of tubular ceramic portions) for electrical insulation capped by a number of end members (e.g., without limitation, metal components, such as metal end plates; end caps; seal cups) to form an envelope in which a partial vacuum may be drawn. The ceramic section is typically cylindrical; however, other suitable cross-sectional shapes may be used.
When the separable contacts are opened with current flowing through the vacuum interrupter, a metal-vapor arc is struck between the contact surfaces. This arc continues until the current is interrupted, typically as the current goes through a zero crossing. In order to prevent the metal vapor from condensing on the ceramic insulator, a generally cylindrical metal vapor shield is typically provided between the contacts and the ceramic inside the vacuum envelope.
Known vacuum interrupters may include any number of ceramic insulators coupled together. Employing two ceramic insulators requires burdensome methods to align the ceramic insulators in the vacuum interrupter, resulting in significantly higher manufacturing costs. Furthermore, a typical single ceramic insulator has a groove inside the ceramic insulator into which an insert is placed to support the vapor shield. However, machining the groove results in micro cracks in the ceramic insulator, which in turn leads to weak spots in terms of insulation. Another method of assembling a vacuum interrupter involves employing a protrusion in the center of the ceramic insulator and deforming the vapor shield around the protrusion. Known drawbacks of such a configuration are that the vapor shield is loose, and also that complex tooling is required for assembly. An additional design involves metalizing one or more of the sides of an internal protrusion and brazing the vapor shield to the protrusion. Such a configuration is significantly expensive to manufacture.
There is, therefore, room for improvement in vacuum interrupters and in retaining clips therefor.
There is also room for improvement in methods of assembling vacuum interrupters.